In the electroplating industry it is common to electroplate metals such as copper, nickel, tin, and tin alloys onto various base metals and/or on top of previously applied plated coatings. The surface to be plated must be as clean and free of metal oxides as is practical in order to ensure a uniform, smooth, adherent deposition of plated metal during the electrodeposition process. Therefore, during processing, the substrates or parts to be plated pass through a series of cleaning and/or activation solutions prior to each electroplating operation. Normally, these cleaning and activation solutions are either strongly alkaline to achieve good detergency and therefore cleaning ability and/or strongly acidic to remove surface oxides through etching of the metal surface which “under-cuts” the oxide thereby facilitating its removal.
In certain applications, particularly in electroplating operations for electronic components, the substrate cannot be exposed to strongly alkaline or strongly acidic solutions. This is the case with, for example, semiconductor wafers which contain sensitive dielectric and metallized materials of chip construction, passive components such as multi-layer chip capacitors which contain pH sensitive materials of construction, or printed circuit board (PCB) applications with acid- or alkaline-sensitive materials of construction. In such applications, the traditional alkaline or acidic cleaning and activation solutions cannot be implemented without detrimentally affecting the components. It has been necessary in such applications to eliminate or minimize oxide formation on surfaces to be electroplated through implementation of extremely careful handling or processing techniques, or to simply process the parts to be plated without a cleaning/activation step, thereby compromising deposit quality.
What is needed for such pH sensitive applications is an effective near neutral pH cleaning/activation solution that enhances the ability of the metal surfaces to receive metal electrodeposits thereon. This need is now met by the present invention.